The present development is for a silica additive for use in rubbers and similar cross-linked materials having a silicon atom intercalated within an oxygenated framework. The additive can be used in rubbers, plastics or similar cross-linked materials to modify the physical characteristics of the material.
Specialty chemicals are frequently added to rubbers and plastics during the manufacturing process to aid in the production and life-expectancy of the finished product. For example, stearic acid and other high molecular weight fatty acids aid in the dispersion of filler materials, such as carbon black, in the rubber. Further, the additives may reduce the milling time required during processing.
Precipitated silica is a common additive in rubbers and plastics because it reinforces and strengthens the materials. Precipitated silica also acts as an abrasion resistance aid in rubber tires. But, raw precipitated silica is usually in a highly agglomerated state, of small ultimate particle size, and exhibits a large amount of particle surface area. Such agglomeration is difficult to eliminate during the rubber or plastic compounding process, resulting in a finished rubber or plastic compound that contains a significant number of precipitated silica agglomerates. The presence of these agglomerates, in combination with the relatively large amount of particle surface area, promotes the production of a finished product that may have a lower tensile strength, less elongation, poorer cure properties and lower tear strength than desired. Precipitated silica agglomeration can be reduced through the use of longer term or more intense compounding processes, but to do so increases the production time and costs.
Fused and crystalline silica can be processed to have a particle size similar to precipitated silica but, typically, a larger particle size distribution is used when using these forms of silica in other unrelated applications. The cost of processing fused and crystalline silica to a mesh size similar to precipitated silica is prohibitive, and along with health hazards associated with crystalline silica makes them unattractive as additives in rubber and plastics.
The present development uses fused silica and crystalline silica with typically available particle sizes in conjunction with a silica additive (HDI). The present development results in a compound that resists the formation of aggregates and more readily disperses in rubbers and plastics. The present development increases the physical properties of the rubber and plastics without adverse effects. The present development, which utilizes more readily available fused and crystalline silica, is also more economical to use than precipitated silica
Thus, the fused and crystalline silica with HDI additive in the present development results in a more economic additive to the rubber/plastics industries with superior physical properties as compared to using precipitated silica as the additive.